Ok, gaming story time.
We were playing Dungeon of the Mad Mage. On one of the levels (I'm avoiding spoilers here), we met a Drow outpost - the main town of the drow was somewhere else. Now, we went in, crushed the outpost and kept one of them alive. And, when I say crushed, I mean it. I don't think we lost so much as a hit point. Now, my very frightening Paladin of Asmodeus tells our prisoner that we will release her to return to her people. We don't want to fight, but, we will if we have too. Just stay out of our way. We've just proven that you are no match for us, we're not interested in you, just stay out of our way.
So, we do a few things, spend some time doing stuff, and then wander into the drow town (mostly by accident since we were pretty much just aimlessly wandering looking for something else). Of course, the entire town comes out to attack us. Tries to mob us.
The entire fight, I'm saying (both in and out of character), We had zero interest in this fight. This is entirely your fault.
Wound up spending most of an entire session dice rolling our way through the fights.
Now, how I would have handled that is entirely different. The released drow, terrified because we just obliterated all the others with ease, goes back to her people, tells them to give us a wide berth and be really polite if we do happen to venture close.
But, of course that didn't happen. Silly me for forgetting the cardinal rule of D&D which is that you must kill every single thing you meet, otherwise, you're just wasting your time.
I'd argue that it's very much a failure of the DM's imagination if they cannot think of why the defeated bad guys stay defeated and don't monkey's paw every single thing the party does.